Jellyfish envenoming syndromes: unknown toxic mechanisms and unproven therapies

Isolation, Structure Determination, and Synthesis of Cyclic Tetraglutamic Acids from Box Jellyfish Species Alatina alata and Chironex yamaguchii

Cubozoan nematocyst venoms contain known cytolytic and hemolytic proteins, but small molecule components have not been previously reported from cubozoan venom. We screened nematocyst extracts of Alatina alata and Chironex yamaguchii by LC-MS for the presence of small molecule metabolites. Three isomeric compounds, cnidarins 4A (1), 4B (2), and 4C (3), were isolated from venom extracts and characterized by NMR and MS, which revealed their planar structure as cyclic γ-linked tetraglutamic acids. The full configurational assignments were established by syntheses of all six possible stereoisomers, comparison of spectral data and optical rotations, and stereochemical analysis of derivatized degradation products. Compounds 1-3 were subsequently detected by LC-MS in tissues of eight other cnidarian species. The most abundant of these compounds, cnidarin 4A (1), showed no mammalian cell toxicity or hemolytic activity, which may suggest a role for these cyclic tetraglutamates in nematocyst discharge.

Severe Cardiac Failure Associated with Presumed Jellyfish Sting. Irukandji Syndrome?

We present a retrospective review of twelve cases of Irukandji syndrome associated with pulmonary oedema. This is a life-threatening envenoming due to a presumed jellyfish sting throughout Northern Australia, although only one case occurred outside North Queensland.

Patients presented with significant and ongoing pain, tachycardia and hypertension. Half the patients became hypotensive requiring inotropic support. Cardiac echocardiography revealed significant cardiac dysfunction. Six patients required ventilatory support. There was no death reported due to pulmonary oedema, but one patient died of intracerebral haemorrhage.

We believe patients may develop a toxin associated cardiomyopathy, and jellyfish other than Carukia barnesi may be responsible. As there is confusion with nomenclature, Carukia barnesi should be known as the Barnes jellyfish, and the diagnosis of cardiotoxic marine envenoming is suggested for any patient who has been stung by a jellyfish, develops no or minimal skin markings, and develops cardiogenic pulmonary oedema associated with Irukandji syndrome.

Early Experience with Magnesium Administration in Irukandji Syndrome

The administration of magnesium sulphate is a proposed novel therapy for Irukandji syndrome1. In this non-randomized, unblinded case series, data from ten patients who received magnesium salts are reviewed. Magnesium sulphate boluses of 10 to 20 mmol, in the six patients for which there was adequate data, reduced pain scores immediately after administration from 8.7±1.5 to 2.8±2.8 (Wilcoxon rank-sum test, P=0.03). In ten patients blood pressure decreased with a mean difference of −18 mmHg in mean arterial pressure. Magnesium requirements in individual patients varied markedly. Pain on injection occurred in four patients, three of whom had received peripherally administered magnesium chloride, and one patient reported transient ptosis after administration of magnesium sulphate 166 mmol over 18 hours in the setting of severe Irukandji syndrome.

Magnesium sulphate administration appears to attenuate pain and hypertension in Irukandji syndrome and warrants further evaluation in this setting.

Efficacy of Topical Treatments for Chrysaora chinensis Species: A Human Model in Comparison with an In Vitro Model

OBJECTIVES

This study sought to create a model for testing topical treatment of jellyfish stings. It sought to determine which treatments 1) stimulate/inhibit nematocyst discharge; 2) decrease pain; and 3) decrease skin inflammation; it also sought to discover whether there is a clinical correlation between stimulated nematocyst discharge observed in vitro to the pain and erythema experienced by humans stung by a particular species of jellyfish, C chinensis.

METHODS

Chrysaora chinensis stung 96 human subjects, who were then treated with isopropyl alcohol, hot water, acetic acid, papain meat tenderizer, lidocaine, or sodium bicarbonate. Pain and erythema were measured. In a separate experiment, nematocysts were examined microscopically after exposure to the same topical treatments used in the human experiment.

RESULTS

Forearms treated with papain showed decreased mean pain over the first 30 minutes after being stung, relative to placebo, although only by a small amount. The other topical treatments tested did not reach statistical significance. Sodium bicarbonate may reduce erythema after 30 minutes of treatment; sodium bicarbonate and papain may reduce erythema at 60 minutes. The other topical treatments tested did not reach statistical significance. Nematocyst discharge in vitro occurred when tentacles of C chinensis were exposed to acetic acid or isopropyl alcohol. Sodium bicarbonate, papain, heated water, and lidocaine did not induce nematocyst discharge.

CONCLUSIONS

Papain-containing meat tenderizer used as a topical treatment for C chinensis stings may decrease pain. Although there is published experimental support for the concept that in vitro nematocyst discharge correlates with in vivo human pain perception, no definitive randomized controlled trial, including ours, has yet provided incontrovertible evidence of this assertion. Despite this study's limitations, it presents a viable basis for future human studies looking at the efficacy of topical treatments for jellyfish stings.

Jellyfish Stings: A Practical Approach

Jellyfish have a worldwide distribution. Their stings can cause different reactions, ranging from cutaneous, localized, and self-limited to serious systemic or fatal ones, depending on the envenoming species. Several first aid treatments are used to manage such stings but few have evidence behind their use. This review of the literature describes and discusses the different related first aid and treatment recommendations, ending with a summarized practical approach. Further randomized controlled trials in this field are needed.

Rapid short term and gradual permanent cardiotoxic effects of vertebrate toxins from Chironex fleckeri (Australian box jellyfish) venom

The vertebrate cardiotoxic components of the venom produced by the Australian box jellyfish, Chironex fleckeri, have not previously been isolated. We have uncovered for the first time, three distinct cytotoxic crude fractions from within the vertebrate cardiotoxic peak of C. fleckeri venom by monitoring viability of human muscle cells with an impedance based assay (ACEA xCELLigence system) measuring cell detachment as cytotoxicity which was correlated with a reduction in cell metabolism using a cell proliferation (MTS) assay. When the effects of the venom components on human cardiomyocytes and human skeletal muscle cells were compared, two fractions were found to specifically affect cardiomyocytes with distinct temporal profiles (labelled Crude Toxic Fractions (CTF), α and β). A third fraction (CTF-γ) was toxic to both muscle cell types and therefore not cardio specific. The vertebrate, cardio specific CTF-α and CTF-β, presented distinct activities; CTF-α caused rapid but short term cell detachment and reduction in cell metabolism with enhanced activity at lower concentrations than CTF-β. This activity was not permanent, with cell reattachment and subsequent increased metabolism of heart muscle cells observed when exposed to all but the highest concentrations of CTF-α tested. The cytotoxic effect of CTF-β took twice as long to act on the cells compared to CTF-α, however, the activity was permanent. Furthermore, we showed that the two fractions combined have a synergistic effect causing a much stronger and faster cell detachment (death) when combined than the sum of the individual effects of each toxin. These data presented here improves the current understanding of the toxic mechanisms of the Australian box jellyfish, C. fleckeri, and provides a basis for in vivo research of these newly isolated toxic fractions.

Interventions for the symptoms and signs resulting from jellyfish stings

BACKGROUND

Jellyfish envenomations are common amongst temperate coastal regions and vary in severity depending on the species. Stings result in a variety of symptoms and signs, including pain, dermatological reactions and, in some species, Irukandji syndrome (including abdominal/back/chest pain, tachycardia, hypertension, sweating, piloerection, agitation and sometimes cardiac complications). Many treatments have been suggested for the symptoms and signs of jellyfish stings. However, it is unclear which interventions are most effective.

OBJECTIVES

To determine the benefits and harms associated with the use of any intervention, in both adults and children, for the treatment of jellyfish stings, as assessed from randomised trials.

SEARCH METHODS

We searched the following electronic databases in October 2012 and again in October 2013: the Cochrane Central Register of Controlled Trials (CENTRAL;The Cochrane Library, Issue 9, 2013); MEDLINE via Ovid SP (1948 to 22 October 2013); EMBASE via Ovid SP (1980 to 21 October 2013); and Web of Science (all databases; 1899 to 21 October 2013). We also searched reference lists from eligible studies and guidelines, conference proceedings and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) and contacted content experts to identify trials.

SELECTION CRITERIA

We included randomised controlled trials that compared any intervention(s) to active and/or non-active controls for the treatment of symptoms and signs of jellyfish sting envenomation. No language, publication date or publication status restrictions were applied.

DATA COLLECTION AND ANALYSIS

Two review authors independently conducted study selection and data extraction and assessed risk of bias using a standardised form. Disagreements were resolved by consensus with a third review author when necessary.

MAIN RESULTS

We included seven trials with a total of 435 participants. Three trials focused on Physalia (Bluebottle) jellyfish, one trial on Carukia jellyfish and three on Carybdea alata (Hawaiian box) jellyfish. Two ongoing trials were identified.Six of the seven trials were judged as having high risk of bias. Blinding was not feasible in four of the included trials because of the nature of the interventions. A wide range of interventions were assessed across trials, and a wide range of outcomes were measured. We reported results from the two trials for which data were available and reported the effects of interventions according to our definition of primary or secondary outcomes.Hot water immersion was superior to ice packs in achieving clinically significant (at least 50%) pain relief at 10 minutes (one trial, 96 participants, risk ratio (RR) 1.66, 95% confidence interval (CI) 1.01 to 2.72; low-quality evidence) and 20 minutes (one trial, 88 participants, RR 2.66, 95% CI 1.71 to 4.15; low-quality evidence). No statistically significant differences between hot water immersion and ice packs were demonstrated for dermatological outcomes.Treatment with vinegar or Adolph's meat tenderizer compared with hot water made skin appear worse (one trial, 25 participants, RR 0.31, 95% CI 0.14 to 0.72; low-quality evidence).Adverse events due to treatment were not reported in any trial.

AUTHORS' CONCLUSIONS

This review located a small number of trials that assessed a variety of different interventions applied in different ways and in different settings. Although heat appears to be an effective treatment for Physalia (Bluebottle) stings, this evidence is based on a single trial of low-quality evidence. It is still unclear what type of application, temperature, duration of treatment and type of water (salt or fresh) constitute the most effective treatment. In addition, these results may not apply to other species of jellyfish with different envenomation characteristics. Future research should further assess the most effective interventions using standardised research methodology.

Isolated severe median mononeuropathy caused by a jellyfish sting

Neuropathies caused by jellyfish stings are extremely rare and poorly studied. A 20-year-old female patient was stung on the volar aspect of the right forearm by an unidentified species of jellyfish. Local cutaneous reaction was followed within few days by severe median mononeuropathy, involving the motor and sensory branches to the hand and forearm but sparing the palmar branch. The patient had neuropathic pain relieved by pregabaline. Electrodiagnostic studies confirmed a demyelinating lesion. Ultrasound and magnetic resonance imaging of the median nerve revealed uniform swelling with mild uptake of contrast along the forearm. Within 2 months, strength improved significantly, pain subsided, and numbness partially resolved. Literature review and discussion of the possible mechanisms and implications of this rare effect of marine animal envenomation is presented. Jellyfish sting may cause focal mononeuropathies most probably because of the local effects of the toxins.

Jellyfish stings and their management: a review

Jellyfish (cnidarians) have a worldwide distribution. Despite most being harmless, some species may cause local and also systemic reactions. Treatment of jellyfish envenomation is directed at: alleviating the local effects of venom, preventing further nematocyst discharges and controlling systemic reactions, including shock. In severe cases, the most important step is stabilizing and maintaining vital functions. With some differences between species, there seems to be evidence and consensus on oral/topical analgesics, hot water and ice packs as effective painkillers and on 30 s application of domestic vinegar (4%-6% acetic acid) to prevent further discharge of unfired nematocysts remaining on the skin. Conversely, alcohol, methylated spirits and fresh water should be carefully avoided, since they could massively discharge nematocysts; pressure immobilization bandaging should also be avoided, as laboratory studies show that it stimulates additional venom discharge from nematocysts. Most treatment approaches are presently founded on relatively weak evidence; therefore, further research (especially randomized clinical trials) is strongly recommended. Dissemination of appropriate treatment modalities should be deployed to better inform and educate those at risk. Adequate signage should be placed at beaches to notify tourists of the jellyfish risk. Swimmers in risky areas should wear protective equipment.

Randomised trial of magnesium in the treatment of Irukandji syndrome

OBJECTIVES

Irukandji syndrome is a distressing condition characterised by pain, hypertension and tachycardia. Some develop cardiac failure and there have been two reported deaths. Magnesium sulphate has become the standard of care despite minimal evidence. The aim of this study was to investigate if magnesium would reduce analgesic requirement and length of stay for patients with Irukandji syndrome.

METHODS

This was a double-blind, randomised controlled clinical trial. Patients with Irukandji syndrome who required parenteral opioid analgesia were randomised to receive either 10 mmol of magnesium as a bolus, and then a 5 mmol/h magnesium infusion for 6 h or saline. Fentanyl patient-controlled analgesia was commenced to allow patients to self-regulate their pain relief. The primary outcome measure of the study was comparison of total analgesic requirements between the two groups. The secondary outcome measure was to compare length of stay.

RESULTS

The study ran from November 2003 to May 2007. Thirty-nine patients were enrolled in the study; 26 were male with a median age of 28. Twenty-two received magnesium. There was no significant difference in the morphine equivalent dose used, peak CK, peak troponin, peak pulse, peak blood pressure, peak mean arterial pressure (MAP), percentage MAP rise and length of stay for those receiving magnesium compared with placebo.

CONCLUSION

Our study did not demonstrate a benefit in the use of magnesium in the treatment of Irukandji syndrome. As such the current use of magnesium needs to be reconsidered until there is good evidence to support its use.

Direct cardiac toxicity of the tentacle-only extract from the jellyfish Cyanea capillata demonstrated in isolated rat heart

Previous studies in our laboratory have shown that the cardiotoxicity is the main reason for rat death caused by tentacle-only extract from jellyfish Cyanea capillata. However, the direct cardiotoxicity in vitro and its mechanisms of toxic action remain unclear. The current studies were performed by using the Langendorff-perfused isolated heart model, which showed a dose-dependent hemodynamic and electrocardiogram changes. Heart injury-related enzymes increased. Histopathological analysis showed early ischemic damage in the myocardium. The Ca channel blockers nifedipine and verapamil led to a marked improvement in recovery of cardiac function, including heart rate, left ventricular developed pressure, positive and negative first derivatives of intraventricular pressure, coronary flow, left ventricular end-diastolic pressure, and electrocardiogram changes. Tentacle-only extract-induced cardiac dysfunction could be partly improved by the pretreatments of both propranolol and phentolamine, but not by either atropine or neostigmine at all. In conclusion, we have verified the direct cardiotoxicity of tentacle-only extract from jellyfish C. capillata by the Langendorff isolated heart model, which consisted of 3 separate parts: sinoatrial node malfunction, cardiomyocyte injury, and coronary spasm. The potential mechanism might be attributed to the overactivation of L-type Ca channel, β- and α-adrenergic receptors, but not cholinergic receptors.

Review of Fatal and Severe Cases of Box Jellyfish Envenomation in Thailand

The study aimed to describe severe and fatal cases of box jellyfish stings in Thailand. Medical records were reviewed and patients, relatives, health staffs, and witnesses were interviewed. The pictures of suspected box jellyfish were sent via e-mail to experts in the toxic jellyfish network for further identification. There were at least 8 cases of box jellyfish envenomation, with 4 fatal and 4 near-fatal cases. There were an equal number of male and female patients from 4 to 26 years of age. In each case, there was immediate severe pain followed by systemic reactions. Immediately after exposure to the sting, 7 victims collapsed experiencing severe pain at the tentacle marks, respiratory failure, and cardiac arrest. All patients had tentacle marks on their bodies. In none of the fatal cases was vinegar applied to the tentacle marks as first aid, but 3 out of the 4 near-fatal cases were treated with a vinegar application.

A pharmacological investigation of the venom extract of the Australian box jellyfish, Chironex fleckeri, in cardiac and vascular tissues

The pharmacology of Australian box jellyfish, Chironex fleckeri, unpurified (crude) nematocyst venom extract (CVE) was investigated in rat isolated cardiac and vascular tissues and in anaesthetised rats. In small mesenteric arteries CVE (0.01-30 μg/ml) caused contractions (EC(50) 1.15±0.19 μg/ml) that were unaffected by prazosin (0.1 μM), bosentan (10 μM), CGRP(8-37) (1 μM) or tetrodotoxin (1 μM). Box jellyfish antivenom (5-92.6 units/ml) caused rightward shifts of the CVE concentration-response curve with no change in the maximum. In the presence of l-NAME (100 μM) the sensitivity and maximum response to CVE were increased, whilst MgSO(4) (6 mM) decreased both parameters. CVE (1-10 μg/ml) caused inhibition of the contractile response to electrical sympathetic nerve stimulation. Left atrial responses to CVE (0.001-30 μg/ml) were bi-phasic, composed of an initial positive inotropy followed by a marked negative inotropy and atrial standstill. CVE (0.3 μg/ml) elicited a marked decrease in right atrial rate followed by atrial standstill at 3 μg/ml. These responses were unaffected by 1 μM of propranolol, atropine or CGRP(8-37). Antivenom (54 and 73 units/ml) caused rightward shifts of the CVE concentration-response curve and prevented atrial standstill in left and right atria. The effects of CVE do not appear to involve autonomic nerves, post-synaptic α(1)- or β(1)-adrenoceptors, or muscarinic, endothelin or CGRP receptors, but may occur through direct effects on the cardiac and vascular muscle. Box jellyfish antivenom was effective in attenuating CVE-induced responses in isolated cardiac and vascular tissues.

Irukandji sydrome in the Torres Strait: a series of 8 cases

OBJECTIVE

To review the presentations of a series of patients with suspected Irukandji syndrome in the Torres Strait, where the syndrome has hitherto been unknown or undocumented, in order to identify at-risk groups and improve the management of this condition in the region.

METHODS

A mixed retrospective-prospective review of eight cases of patients with suspected Irukandji syndrome in the Torres Strait, with a focus on the differences between the clinical presentations and patient outcomes.

RESULTS

Irukandji syndrome is the most likely explanation, based on current knowledge, of this series of marine envenomation syndromes in the Torres Strait. The syndrome appears to be more common in the monsoon season and young, Torres Strait Islander males likely represent a high-risk group in the region.

CONCLUSIONS

The Torres Strait can be added to the growing list of regions where Irukandji syndrome has been documented. The clinical picture, including time to onset of symptoms, constellation of symptoms and signs, analgesic requirement and time to recovery, can differ markedly between patients. There is a need for health promotion and education of health staff and the public regarding the risks, symptoms and signs of this condition. There is also a clear need for the use of case definitions and standardised management approaches for Irukandji syndrome, while the health community awaits the results of ongoing research into the pathophysiology and improved treatments for this interesting but dangerous tropical marine envenomation syndrome.

Intracerebral hemorrhage and death after envenoming by the jellyfish Carukia barnesi

INTRODUCTION

Irukandji syndrome is because of envenoming by a number of small jellyfish. It results in a delayed onset of generalized pain, sweating hypertension, and tachycardia. There is no antivenom.

CASE REPORT

A 44-year-old healthy male was stung while swimming in NE Australia. He rapidly developed Irukandji syndrome. He had a rapid deterioration in conscious level because of an intracerebral hemorrhage. He developed left ventricular failure with an elevated troponin (34 mcg/L, N < 0.4) requiring inotropic support. He progressed to brain death and died on day 13 poststing. Nematocysts recovered from the patient skin were consistent with a large Carukia barnesi.

DISCUSSION

This is the first case of a death because of Irukandji syndrome where the jellyfish Carukia barnesi has been demonstrated to the causative creature.

Evolution of box jellyfish (Cnidaria: Cubozoa), a group of highly toxic invertebrates

Cubozoa (Cnidaria: Medusozoa) represents a small clade of approximately 50 described species, some of which cause serious human envenomations. Our understanding of the evolutionary history of Cubozoa has been limited by the lack of a sound phylogenetic hypothesis for the group. Here, we present a comprehensive cubozoan phylogeny based on ribosomal genes coding for near-complete nuclear 18S (small subunit) and 28S (large subunit) and partial mitochondrial 16S. We discuss the implications of this phylogeny for our understanding of cubozoan venom evolution, biogeography and life-history evolution. Our phylogenetic hypothesis suggests that: (i) the last common ancestor of Carybdeida probably possessed the mechanism(s) underlying Irukandji syndrome, (ii) deep divergences between Atlantic and Indo-Pacific clades may be explained by ancient vicariant events, and (iii) sexual dimorphism evolved a single time in concert with complex sexual behaviour. Furthermore, several cubozoan taxa are either para- or polyphyletic, and we address some of these taxonomic issues by designating a new family, Carukiidae, a new genus, Copula, and by redefining the families Tamoyidae and Tripedaliidae. Lastly, cubozoan species identities have long been misunderstood and the data presented here support many of the recent scientific descriptions of cubozoan species. However, the results of a phylogeographic analysis of Alatina moseri from Hawai'i and Alatina mordens from Australia indicate that these two nominal species represent a single species that has maintained metapopulation cohesion by natural or anthropogenic dispersal.

Irukandji syndrome case series from Australia's Tropical Northern Territory

STUDY OBJECTIVE

We describe Irukandji syndrome (a painful hypercatecholaminergic condition caused by jellyfish envenoming) in Australia's Northern Territory.

METHODS

We collected prospectively a standardized data set on patients presenting to health facilities in the Northern Territory. Additional cases were identified retrospectively. Data collected included demographic, geographic, seasonal, and environmental features, as well as sting details, clinical manifestations, investigations, management, and outcomes.

RESULTS

From 1990 to 2007, Irukandji syndrome affected 87 people. Age ranged from 1 to 51 years (64% male victims; 41% children [63% indigenous]). Activities associated with stings included snorkeling or scuba diving (35%) and swimming (29%). Stings commonly occurred in water greater than 2 m deep (63%), with fine weather (73%) and still or light breeze (70%). Seasonal variation was bimodal; peaks in May and October corresponded to prevailing offshore winds in the Darwin and Gove areas, respectively. Pain was severe (65%), with rapid onset (<30 minutes in 79%). Sting lesions (visible in 63%) were mild, and nematocysts (detected in 7 cases) had variable morphology. Systemic features were common, including hypertension and ECG abnormalities. Severe complications included troponin-level increases (2 cases) and cardiomyopathy with ventricular tachycardia (1 case), but no fatalities. Management included vinegar as first aid (66%), parenteral opioids (70%) (range 2 to 82.5 mg morphine equivalents in adults), and magnesium sulfate (3 cases). Hospital admission (49%) and aeromedical retrieval (16%) were commonplace.

CONCLUSION

Irukandji syndrome in the Northern Territory was clinically consistent with previous studies but had distinct seasonal, geographic, and environmental features. Indigenous children in remote coastal communities are at risk, and there is room for improvement in prevention and management.

In vivo effects of cnidarian toxins and venoms

Cnidarians (Coelenterates), a very old and diverse animal phylum, possess a wide variety of biologically active substances that can be considered as toxins. Anthozoan toxins can be classified into two chemically very different groups, namely polypeptide toxins isolated from sea anemones and diterpenes isolated from octocorals. Cubozoan and scyphozoan protein toxins have been the most elusive cnidarian toxins to investigate - despite a tremendous effort in the past few decades, very few of these large, relatively unstable protein toxins were isolated, but recently this has been achieved for cubozoan venoms. Hydrozoans mainly contain large proteins with physiological mechanisms of action similar to the sea anemone and jellyfish pore-forming toxins. This article will focus on the in vivo physiological effects of cnidarian toxins and venoms; their actions at the cellular level will only be considered to understand their actions at the organ and whole animal levels. An understanding of mechanisms underlying the in vivo toxic effects will facilitate the development of more effective treatments of cnidarian envenomations.

Eight microsatellite loci for the Irukandji syndrome-causing carybdeid jellyfish, Carukia barnesi (Cubozoa, Cnidaria)

Microsatellites are high-resolution genetic markers that may be applied to examine parentage, population structure and the direction and extent of dispersal. Here we present eight polymorphic microsatellite loci developed for the carybdeid jellyfish, Carukia barnesi. The loci were developed from a microsatellite-enriched, partial genomic DNA library and tested for polymorphism on animals from each of two geographically distinct populations, Lizard Island and Double Island, from the Great Barrier Reef. The number of alleles observed for each locus ranged from 7 to 19.

Comparative study on the cell toxicity and enzymatic activity of two northern scyphozoan species Cyanea capillata (L.) and Cyanea lamarckii (Péron & Léslieur)

Two species of venomous pelagic cnidaria are compared according to their enzymatic, cytotoxic and haemolytic potency. The widely distributed jellyfish Cyanea capillata and Cyanea lamarckii were collected in the North Sea at the coasts of the Orkney Island and the Island of Helgoland. Purified cnidocyst extracts from fishing and mesenteric tentacles were prepared and tested for their bioactivity. The haemolysis induced by toxins of C. capillata was determined with respect to organism size and toxigenic organs. The haemolytic activity of the related species C. lamarckii was documented for the first time. Dose dependent haemolytic activities have been detected by means of protein equivalents at concentrations above 20mug(protein)/mL. Extracts of fishing tentacle cnidocysts showed a less potent haemolytic activity compared to extracts of mesenteric tentacles. In vitro studies with permanent cells of a hepatoma cell line have shown a time and concentration dependent loss of cell vitality up to 90% at 33.3mug(protein)/mL (10mug(protein)/10(5) cells). Supplementing the cell based toxicity tests an enzyme assay was performed to measure a phospholipase A(2) (PLA(2)) activity. A PLA(2)-like activity could be demonstrated in cnidocysts extracts prepared from mesenteric and fishing tentacles of both jellyfish species.

Cardiovascular effects of Nemopilema nomurai (Scyphozoa: Rhizostomeae) jellyfish venom in rats

Over the past few years, populations of the giant jellyfish Nemopilema nomurai (Scyphozoa: Rhizostomeae) have increased dramatically in the waters of China, Korea, and Japan without any definitive reason. This has resulted in severe damage to fisheries in the areas. During a pilot study, we observed that the venom of N. nomurai produced a functional cardiac depression in mice. However, the mechanism of action was not examined. In the present study, we investigated the cardiovascular effects of nematocyst-derived venom from N. nomurai in anesthetized rats. Venom (0.1-2.4 mg protein/kg, i.v.) produced dose-dependent hypotension (65+/-12% of initial at a cumulative dose of 3 mg/kg) and bradycardia (80+/-5% of initial at a cumulative dose of 3 mg/kg). At the highest dose, this was characterized by a transient decrease in blood pressure (phase 1) followed by a return to basal level and then a slower decrease in blood pressure (phase 2). Venom also produced a decrease in rate and force of contraction in the rat isolated atria. Interestingly, venom induced a contraction of isolated aortic rings which was blocked by felodipine but not by prazosin, suggesting the contraction is mediated by calcium channel activation. These results suggest that the negative inotropic and chronotropic effects of the venom of N. nomurai may be due to a direct effect on the heart.

Jellyfish and other cnidarian envenomations cause pain by affecting TRPV1 channels

Cnidarian envenomations cause a burning-pain sensation of which the underlying mechanisms are unknown. Activation of TRPV1, a non-selective cation channel expressed in nociceptive neurons, leads to cell depolarisation and pain. Here, we show in vitro and in vivo evidence for desensitization-dependent TRPV1 activation in cnidarian envenomations. Cnidarian venom induced a nociceptive reactivity, comparable to capsaicin, in laboratory rats, which could be reduced by the selective TRPV1 antagonist, BCTC. These findings are the first to explain at least part of the symptomology of cnidarian envenomations and provide insights into the design of more effective treatments for this global public health problem.

Prospective study of Chironex fleckeri and other box jellyfish stings in the “Top End” of Australia's Northern Territory

OBJECTIVE

To describe the epidemiology and clinical features of box jellyfish envenoming in the Top End of the Northern Territory and, in particular, confirmed stings from the major Australian box jellyfish, Chironex fleckeri.

DESIGN

Prospective collection of clinical data and skin scrapings or sticky-tape tests for nematocyst identification from patients presenting to Royal Darwin Hospital and remote coastal community health clinics in the Northern Territory, spanning 10 950 km of coastline; analysis of tidal, weather and seasonal data.

PATIENTS

All patients with jellyfish sting details recorded between 1 April 1991 and 30 May 2004.

MAIN OUTCOME MEASURES

Demographic and clinical features, use of C. fleckeri antivenom, and associations between weather, seasonal and tidal factors and confirmed C. fleckeri stings.

RESULTS

Of 606 jellyfish stings documented, 225 were confirmed to have been caused by C. fleckeri. 37% of C. fleckeri stings were in children, 92% occurred during the "stinger season" (1 October to 1 June), 83% occurred in water 1 m or less deep, and 17% occurred while victims were entering the water. Stings were least common on outgoing tides (P < 0.001) and commonest between 15:00 and 18:00 (P < 0.001) and on days with wind speed less than that month's average (P < 0.001). Nearly all victims experienced immediate pain, but this could often be controlled with ice; only 30% required parenteral narcotics and 8% required hospital admission. Cardiorespiratory arrest occurred within several minutes of the sting in the one fatal case, involving a 3-year-old girl with only 1.2 m of visible tentacle contact. C. fleckeri antivenom was given to another 21 patients, none of whom had life-threatening features at the time they were given antivenom.

CONCLUSIONS

Most C. fleckeri stings are not life-threatening; patients who die usually have cardiopulmonary arrest within minutes of the sting. The potential benefit of antivenom and magnesium under these circumstances remains to be shown, but a protocol with their rapid use is recommended if cardiopulmonary arrest has occurred. Unfortunately, this is unrealistic for many rural coastal locations, and the priority remains prevention of stings by keeping people, especially children, out of the sea during the stinger season.

Cardiovascular actions of the venom from the Irukandji (Carukia barnesi) jellyfish: effects in human, rat and guinea-pig tissues in vitro and in pigs in vitro

1. We have investigated the cardiovascular pharmacology of the crude venom extract (CVE) from the potentially lethal, very small carybdeid jellyfish Carukia barnesi, in rat, guinea-pig and human isolated tissues and anaesthetized piglets. 2. In rat and guinea-pig isolated right atria, CVE (0.1-10 microg/mL) caused tachycardia in the presence of atropine (1 micromol/L), a response almost completely abolished by pretreatment with tetrodotoxin (TTX; 0.1 micromol/L). In paced left atria from guinea-pig or rat, CVE (0.1-3 microg/mL) caused a positive inotropic response in the presence of atropine (1 micromol/L). 3. In rat mesenteric small arteries, CVE (0.1-30 microg/mL) caused concentration-dependent contractions that were unaffected by 0.1 micromol/L TTX, 0.3 micromol/L prazosin or 0.1 micromol/L omega-conotoxin GVIA. 4. Neither the rat right atria tachycardic response nor the contraction of rat mesenteric arteries to CVE were affected by the presence of box jellyfish (Chironex fleckeri) antivenom (92.6 units/mL). 5. In human isolated driven right atrial trabeculae muscle strips, CVE (10 microg/mL) tended to cause an initial fall, followed by a more sustained increase, in contractile force. In the presence of atropine (1 micromol/L), CVE only caused a positive inotropic response. In separate experiments in the presence of propranolol (0.2 micromol/L), the negative inotropic effect of CVE was enhanced, whereas the positive inotropic response was markedly decreased. 6. In anaesthetized piglets, CVE (67 microg/kg, i.v.) caused sustained tachycardia and systemic and pulmonary hypertension. Venous blood samples demonstrated a marked elevation in circulating levels of noradrenaline and adrenaline. 7. We conclude that C. barnesi venom may contain a neural sodium channel activator (blocked by TTX) that, in isolated atrial tissue (and in vivo), causes the release of transmitter (and circulating) catecholamines. The venom may also contain a 'direct' vasoconstrictor component. These observations explain, at least in part, the clinical features of the potentially deadly Irukandji syndrome.

Cardiovascular effects and lethality of venom from nematocysts of the box-jellyfish Chiropsalmus quadrigatus (Habu-kurage) in anaesthetized rats

Haemodynamic effects of saline-extracted venom from nematocysts isolated from Chiropsalmus quadrigatus (Habu-kurage) were studied in anaesthetized rats. Intravenous administration of venom (0.2-5 microg protein/kg) produced immediately dose-dependent hypertension and bradycardia. Femoral blood flow transiently increased but calculated femoral vascular conductance decreased. Changes caused by 1 microg/kg of venom were reproducible, and were not affected by prazosin, atropine or BQ123 (ET(A) receptor antagonist) but were significantly attenuated by nicardipine. At doses over 2 microg/kg, hypotension and a decrease in pulse pressure were observed subsequent to transient hypertension. In 5 of 8 rats received 5 microg/kg venom and 6 of 6 rats at 10 microg/kg, death due to irreversible cardiac arrest occurred within 30 min after intravenous injection. However, during nicardipine infusion, venom (10 microg/kg) exerted only modest effects and the rats survived. Heating venom (50 degrees C for 10 min) before injection practically abolished the haemodynamic effects of 10 microg/kg venom, indicating its thermolability. Data show that C. quadrigatus venom has both vasoconstrictor and cardiodepressive effects in rats, and suggest that a calcium channel blocker can protect against the cardiovascular and lethal effects of the venom.

Pharmacologically distinct cardiovascular effects of box jellyfish (Chironex fleckeri) venom and a tentacle-only extract in rats

Using a recently developed technique to extract jellyfish venom from nematocysts, the present study investigated the in vivo cardiovascular effects of Chironex fleckeri venom and tentacle extract (devoid of nematocysts). In anaesthetised rats, venom (10 microg/kg, i.v.) produced a transient pressor response (23+/-4 mmHg) followed, in two of five animals, by cardiovascular collapse. Tentacle extract (100 microg/kg, i.v.) produced a more prolonged hypertensive effect (31+/-3 mmHg) without cardiovascular collapse. Prazosin (50 microg/kg, i.v.) did not have any significant effect on the cardiovascular effects produced by venom. However, prazosin significantly attenuated the pressor response produced by tentacle extract. Ketanserin (1 mg/kg, i.v.) did not have any significant effect on the cardiovascular response of the anaesthetised rat to venom (10 microg/kg, i.v.; 25+/-1 mmHg). Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) was performed to compare the two jellyfish samples used in the present study. In addition to ensuring reproducibility of future studies and allow comparison with previous research. We show, for the first time, that a pure venom sample extracted from C. fleckeri nematocysts and a tentacle extract have cardiovascular effects in the anaesthetised rat which are different and pharmacologically distinct.

The in vivo cardiovascular effects of the Irukandji jellyfish (Carukia barnesi) nematocyst venom and a tentacle extract in rats

Envenoming by Carukia barnesi may produce life-threatening Irukandji syndrome. There is little published on the activity of C. barnesi venom. This is the first study to investigate the in vivo cardiovascular effects of C. barnesi venom and a tentacle extract (devoid of nematocysts). Venom (50 microg/kg or 100 microg/kg, i.v.) produced a pressor response (42+/-3 and 44+/-6 mmHg, respectively; n=4) and increase in heart rate (31+/-5 and 13+/-2 bpm, respectively; n = 4) in anaesthetised rats. These changes were not dose-dependent and were followed by cardiovascular collapse in one of four rats receiving 50 microg/kg and three of four animals receiving 100 microg/kg. Prazosin (50 microg/kg, i.v.) significantly attenuated the venom (50 microg/kg, i.v.)-induced pressor response (-8+/-3 mmHg; P < 0.05; n = 4) and tachycardia (-9+/-4 bpm; P < 0.05; n = 4). Tentacle extract (100 microg/kg; i.v.) produced a pressor response (51+/-12 mmHg; n = 3) and an increase in heart rate (35+/-1 bpm; n = 3) in anaesthetised rats, with no subsequent cardiovascular collapse. The results of this study are consistent with the effects shown by humans envenomed by C. barnesi which are postulated to be a result of catecholamine release. We show, for the first time, that C. barnesi tentacle extract, free of nematocyst material, produces cardiovascular effects which are distinct from those caused by venom derived from isolated nematocysts.

Irukandji syndrome in northern Western Australia: an emerging health problem

OBJECTIVES

(1) To assess the number and severity of episodes of Irukandji syndrome in Broome, Western Australia. (2) To correlate demographic, seasonal, geographic and climatic features of Irukandji stings. (3) To assess treatment of Irukandji syndrome at Broome Health Service. (4) To assess the public health impact.

DESIGN AND SETTING

(1) A retrospective analysis of jellyfish data forms and charts of 111 patients, identified from Broome Health Service Emergency Department with a discharge diagnosis of marine sting between 1 January 2001 and 1 July 2003. (2) Correlation between climate and Irukandji envenomation data.

MAIN OUTCOME MEASURES

Number of patients with Irukandji syndrome; their demographic and environmental features; the clinical syndrome; treatment requirements.

RESULTS

111 patients were prospectively identified with marine stings; 88 were identified with Irukandji syndrome. Non-Irukandji syndrome data were excluded for analysis. The "jellyfish season" extends from January to May, although stings occur all year round. Only 38% of patients had vinegar applied to the sting site before hospital presentation. Signs and symptoms were variable between individuals, with 20% having no signs of sting at all and welts found in 16%. Fifty per cent of patients were hypertensive at presentation. Distress was found in the majority of patients, with 90% requiring opioid analgesia (morphine equivalent: mean, 20 mg; median, 13 mg) and 17% requiring admission. There was one evacuation to Perth with cardiotoxic marine envenomation resulting in pulmonary oedema, which necessitated 4 days in intensive care. Stings were significantly more common when the ambient median temperature was greater than 28.3 degrees C, after midday, on an incoming high tide and on windy days.

CONCLUSION

The rate of envenomation in northern WA is likely to be the highest currently documented in Australia. There is syndromic variability when compared with the north Queensland experience. This implies different causative jellyfish species that are not yet identified. Stings in Broome can be severe and life threatening; there are significant commercial and public health implications as a result. Management at Broome Hospital is contemporary and effective.

The in vivo cardiovascular effects of box jellyfish Chironex fleckeri venom in rats: efficacy of pre-treatment with antivenom, verapamil and magnesium sulphate

Using a new technique to extract venom from the nematocysts, the efficacy of CSL box jellyfish antivenom (AV) and adjunct therapies, verapamil and magnesium sulfate (MgSO(4)), were investigated against the in vivo cardiovascular effects of Chironex fleckeri venom in anaesthetised rats. C. fleckeri venom (30 microg/kg; i.v.) produced a transient hypertensive response followed by hypotension and cardiovascular collapse within 4 min of administration. Prophylactic treatment of anaesthetised rats with CSL box jellyfish AV (3000 U/kg; i.v.) did not have any effect on the venom-induced pressor response, but prevented cardiovascular collapse in four out of 10 animals. Administration of verapamil (20mM@0.25 ml/min; i.v.) either alone or in combination with AV, did not have any effect on the C. fleckeri venom-induced pressor response nor the consequent hypotension or cardiovascular collapse of animals. However, the administration of verapamil negated the partially protective effects of AV. Concurrent artificial respiration of animals with the above treatments did not attenuate the C. fleckeri venom-induced cardiovascular effects. MgSO(4) (0.05-0.07M@0.25 ml/min; i.v.) alone did not have any effect on the venom-induced pressor response nor the consequent cardiovascular collapse of animals. However, although combined AV and MgSO(4) administration could not inhibit the transient pressor effect following the administration of C. fleckeri venom, it prevented cardiovascular collapse in all animals. We show for the first time, the cardiovascular effects of a C. fleckeri venom sample free of tentacular contamination and the potential of MgSO(4) as an adjunct therapy for the treatment of potentially fatal C. fleckeri envenomings.

Country profile: travelling to Australia

Australia has a well-developed tourism industry and health care system. Despite the precautions recommended in this paper, Australia has been virtually free of local outbreaks of life threatening tropical diseases in recent decades. This paper focuses on health and safety issues for travellers to Australia, especially the special precautions for those travelling to more rural and remote areas in outback Australia. Travellers to Australia should be advised that, in general, Australia is a relatively safe country in which to travel, and it has high standards of health and hygiene.